Immunohistochemistry and differential diagnosis of a solitary flat laryngeal xanthoma: a case report.

A 35-year-old woman presented with dyspnea, recurrent laryngitis and gastroesophageal reflux disease. Laryngoscopic examination revealed a yellow lesion on the anterior site of the left true vocal cord. No abnormal lesions were found in other portions of the larynx. The lesion was biopsied and a histological examination showed numerous foamy cells diffusely presented in the stroma of the specimen. Overlying squamous epithelium did not show cellular atypia. On the basis of histological appearance, the possible differential diagnosis included xanthomatous lesion, granular cell tumor or epithelial neoplasia. CD68, S-100 protein and cytokeratin immunoreactivities were investigated. Immuno-histochemically, foamy cells were positive for CD68, indicating a histiocytic origin.